1. Field of the Invention
This invention relates to magnet bodies using novel samarium-iron-nitrogen system permanent magnetic materials excellent in magnetic properties such as the magnetic flux density (Br), the coercive force (Hc) and the maximum energy product ((BH)max) and, more particularly, to extrusion-molded magnetic bodies using samarium-iron-nitrogen system magnetic particles, that is, bond magnets or synthetic-resin-molded magnets which are obtained by using the novel permanent magnet materials and excellent in moldability and flexibility.
2. Description of the Related Art
Suitable permanent magnet materials to be used have stable properties, with the magnetic flux density (Br), the coercive force (Hc) and the maximum energy product ((BH)max) being high. Extensively used magnets using these permanent magnet materials are ferrite magnets, which use barium-ferrite (BaO6Fe.sub.2 O.sub.3) or strontium-ferrite (SrO6Fe.sub.2 O.sub.3), and rare earth system magnets, which use samarium-cobalt (Sm.sub.2 Co.sub.17) and neodymium-iron-boron (Nd.sub.2 Fe.sub.14 B)
Ferrite magnets are inexpensive and ready to manufacture, and are thus finding extensive applications irrespective of whether they are sintered magnets or bond magnets. Neodymium-iron-boron surpasses ferrite magnets and also surpasses samarium-cobalt magnets in magnetic properties. This material, however, is more readily oxidized than samarium-cobalt magnets, and therefore it requires precautions for preventing the oxidation. The samarium-cobalt magnets greatly surpass ferrite magnets in magnetic properties, so that they have long been used. Further researche and development to improve their property have been made, resulting in improvements in their magnetic properties.
The samarium-cobalt magnet, however, has a drawback in that cobalt is an expensive metal. For obtaining an inexpensive magnet, therefore, a permanent magnet material has been desired, which does not require cobalt and has excellent magnetic properties. Recently, a samarium-iron-nitrogen material having excellent magnetic properties comparable to the neodymium-iron-boron magnet, has been obtained in such a method that nitrogen is introduced into the iron crystal lattice of a samarium-iron alloy by holding the alloy in a nitrogen gas at about 500 degrees C. This samarium-iron-nitrogen system material, however, has a drawback in that nitrogen gets out of the iron crystal lattice when its temperature is elevated, so that it could be used for sintered magnets.